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1.

Aim:

To investigate the role of reactive oxygen species (ROS) in oridonin-induced apoptosis and autophagy in HeLa cells.

Methods:

The cell viability was measured using MTT assay. Morphological changes of apoptosis and autophagy were examined using Hoechst 33258 staining and monodansylcadaverine (MDC) staining, respectively. The mitochondrial membrane potential (ΔΨm) was measured using fluorescent dye rhodamine 123. DCF-induced fluorescence was used to measure the intracellular ROS level. Protein expression was examined using Western blot.

Results:

Treatment of HeLa cells with oridonin (20–160 μmol/L) inhibited the cell growth in time- and concentration-dependent manners. The cells treated with oridonin (80 μmol/L) for 24 h displayed marked DNA fragmentation and MDC-positive autophagosomes. In the presence of the specific autophagy inhibitor 3-MA (2 mmol/L), the oridonin-induced apoptosis was significantly enhanced. Treatment of HeLa cells with oridonin (20–120 μmol/L) induced intracellular ROS generation in a concentration-dependent manner. In the presence of the ROS scavenger NAC (5 mmol/L), the oridinin-induced ROS generation was markedly reduced. NAC (5 mmol/L) or non-thiol antioxidant catalase (1000 U/mL) significantly reduced the oridonin-induced inhibition of cell growth and apoptosis. Furthermore, oridonin significantly reduced ΔΨm, which was blocked by NAC. Oridonin markedly increased Bax expression in mitochondria, and decreased Bcl-2 expression in both the cytosol and mitochondria. Oridonin also markedly increased the phosphorylation of Bcl-2 in the cytosol. All the effects were blocked by NAC. Oridonin increased the levels of caspase-3 and caspase-8, and decreased the expression of pro-caspase 3 and pro-caspase 9, which were blocked by NAC.

Conclusion:

ROS plays a critical role in oridonin-induced apoptosis and autophagy.  相似文献   

2.
3.
Bcl-2 family proteins are key regulators of the intrinsic apoptotic pathway, either facilitating (Bax, Bak, BH3-only) or inhibiting (Bcl-2, Bcl-xL, Mcl-1, A1) mitochondrial release of apoptogenic factors. The role of caspases in this process is a matter of controversy. We have analyzed the relative contribution of caspases and Bcl-2 family of proteins in the induction phase of apoptosis triggered by doxorubicin in two p53-deficient leukemia cell lines, Jurkat and U937. First, we have found that caspases are dispensable for the induction phase of doxorubicin-induced apoptosis in both cell lines but they are needed to speed up the execution phase in Jurkat cells, not expressing Bax. Thus, down-regulation of Bak expression by siRNA significantly prevented doxorubicin-induced apoptosis in Jurkat but not in U937 cells. Reduction of Mcl-1 protein levels with siRNA increased sensitivity to apoptosis in both cell lines. Moreover, our results indicate that the contribution of BH3-only proteins to apoptosis is cell line specific. In Jurkat cells simultaneous silencing of Bim and PUMA was necessary to reduce doxorubicin-induced apoptosis. In U937 cells silencing of Bim or Noxa reduced sensitivity to doxorubicin. Immunoprecipitation experiments discarded an interaction between Mcl-1 and Bak in both cell lines and underscored the role of Bim and PUMA as mediators of Bax/Bak activation.  相似文献   

4.

Aim:

To elucidate the molecular mechanisms underlying the immunosuppressive effects of emodin isolated from Rheum palmatum L.

Methods:

Human T cells were isolated from the peripheral venous blood of 10 healthy adult donors. Cell viability was analyzed with MTT assay. AO/EB and Annexin V/PI staining and DNA damage assay were used to detect cell apoptosis. Fluorescence staining was used to detect the levels of ROS, the mitochondrial membrane potential and intracellular Ca2+. Colorimetry was used to detect the levels of MDA and total SOD and GSH/GSSG ratio. The expression and activity of caspase-3, -4, and -9 were detected with Western blotting and a fluorometric assay. Western blotting was also used to detect the expression of Bcl-2, Bax, cytochrome C, and endoplasmic reticulum (ER) markers.

Results:

Emodin (1, 10, and 100 μmol/L) inhibited the growth of human T cells and induced apoptosis in dose- and time dependent manners. Emodin triggered ER stress and significantly elevated intracellular free Ca2+ in human T cells. It also disrupted mitochondrial membrane potential, and increased cytosolic level of cytochrome C, and the levels of activated cleavage fragments of caspase-3, -4, and -9 in human T cells. Furthermore, emodin significantly increased the levels of ROS and MDA, inhibited both SOD level and GSH/GSSG ratio in human T cells, whereas co-incubation with the ROS scavenger N-acetylcysteine (NAC, 20 μmol/L) almost completely blocked emodin-induced ER stress and mitochondrial dysfunction in human T cells, and decreased the caspase cascade-mediated apoptosis.

Conclusion:

Emodin exerts immunosuppressive actions at least partly by inducing apoptosis of human T cells, which is triggered by ROS-mediated ER stress and mitochondrial dysfunction.  相似文献   

5.
Endothelial cell apoptosis, which may alter the integrity of the endothelium and lead to plaque instability, plays a critical role in the development and pathogenesis of atherosclerosis. Exposure of polychlorinated biphenyls (PCBs) is associated with increased risk of atherosclerosis and cardiovascular disease. In our present study, we explored whether exposure to PCB 118 influences endothelial cell apoptosis in vitro and the underlying mechanisms involved. As expected, exposure to PCB 118 increased the intracellular reactive oxygen species (ROS) levels in HUVECs. Increases in apoptosis and Bax/Bcl-2 ratios were observed in PCB 118-treated HUVECs. N-acetyl-l-cysteine (NAC), a ROS scavenger, partially reduced PCB 118-induced apoptosis and Bax/Bcl-2 ratios in HUVECs. Taken together, PCB 118-induced endothelial cell apoptosis was partially initiated by excessive ROS production.  相似文献   

6.
目的:研究四硫化四砷(As4S4)对人胃癌细胞SGC7901增殖的抑制作用及其作用机制。方法:体外培养SGC7901,取对数生长期的细胞分为空白对照组(不加药物)和20、40、60、80μmol/LAs4S4处理组,分别作用24、48、72 h。采用MTT法检测细胞增殖的抑制率,透射电镜观察细胞的形态,流式细胞仪分析细胞的周期分布,逆转录-聚合酶链式反应法和蛋白质印迹法检测作用48 h后细胞中凋亡相关基因Bcl-2、Bax mRNA和蛋白的表达。结果:与空白对照组比较,20(作用48、72 h)、40、60、80μmol/LAs4S4处理组细胞增殖的抑制率明显升高(P<0.01),与浓度和时间呈正相关;从40μmol/L As4S4处理组细胞开始出现凋亡,60μmol/L As4S4处理组细胞开始出现大量凋亡,细胞周期阻滞于S期;与空白对照组比较,As4S4处理组细胞中Bcl-2 mRNA和蛋白表达随As4S4浓度的增加而减弱,Bax mRNA和蛋白表达随As4S4浓度的增加而增强。结论:As4S4具有抑制SGC7901细胞增殖的作用,其机制可能与诱导细胞凋亡、下调Bcl-2表达、上调Bax表达有关。  相似文献   

7.
Nickel compounds are known to be toxic and carcinogenic in kidney and lung. In this present study, we investigated the roles of reactive oxygen species (ROS) and mitochondria in nickel (II) acetate-induced cytotoxicity and apoptosis in the HK-2 human renal cell line. The results showed that the cytotoxic effects of nickel (II) involved significant cell death and DNA damage. Nickel (II) increased the generation of ROS and induced a noticeable reduction of mitochondrial membrane potential (MMP). Analysis of the sub-G1 phase showed a significant increase in apoptosis in HK-2 cells after nickel (II) treatment. Pretreatment with N-acetylcysteine (NAC) not only inhibited nickel (II)-induced cell death and DNA damage, but also significantly prevented nickel (II)-induced loss of MMP and apoptosis. Cell apoptosis triggered by nickel (II) was characterized by the reduced protein expression of Bcl-2 and Bcl-xL and the induced the protein expression of Bad, Bcl-Xs, Bax, cytochrome c and caspases 9, 3 and 6. The regulation of the expression of Bcl-2-family proteins, the release of cytochrome c and the activation of caspases 9, 3 and 6 were inhibited in the presence of NAC. These results suggest that nickel (II) induces cytotoxicity and apoptosis in HK-2 cells via ROS generation and that the mitochondria-mediated apoptotic signaling pathway may be involved in the positive regulation of nickel (II)-induced renal cytotoxicity.  相似文献   

8.
目的:研究白术内酯Ⅰ(atractylenolide Ⅰ)对人胃癌细胞SGC-7901裸鼠移植瘤生长及凋亡相关蛋白Bax、cleaved caspase-3、p53、Bcl-2表达的影响。方法:建立SGC-7901裸鼠移植瘤模型,观察白术内酯Ⅰ对肿瘤生长的影响;TUNEL法检测移植瘤组织中的细胞凋亡;Western blotting检测瘤组织中Bax、Bcl-2、cleaved caspase-3及p53蛋白表达。结果:白术内酯Ⅰ不同程度抑制裸鼠SGC-7901移植瘤的生长,与对照组比较,给药后肿瘤体积(TV,tumor volume)、相对肿瘤体积(RTV,relative tumor volume)和相对肿瘤增殖率[T/C(%),TRTV/CRTV]明显下降;移植瘤组织中凋亡细胞明显增多;白术内酯Ⅰ上调移植瘤组织中Bax、cleaved caspase-3及p53的蛋白表达,下调Bcl-2 的蛋白表达。结论:白术内酯Ⅰ能明显抑制人胃癌细胞SGC-7901裸鼠移植瘤的生长,分子机制主要包括增加Bax、cleaved caspase-3、p53蛋白表达,减少Bcl-2蛋白表达,最终导致肿瘤细胞凋亡。  相似文献   

9.

Aim:

Proteasome inhibitors have been found to suppress glioma cell proliferation and induce apoptosis, but the mechanisms are not fully elucidated. In this study we investigated the mechanisms underlying the apoptosis induced by the proteasome inhibitor MG-132 in glioma cells.

Methods:

C6 glioma cells were used. MTT assay was used to analyze cell proliferation. Proteasome activity was assayed using Succinyl-LLVY-AMC, and intracellular ROS level was evaluated with the redox-sensitive dye DCFH-DA. Apoptosis was detected using fluorescence and transmission electron microscopy as well as flow cytometry. The expression of apoptosis-related proteins was investigated using Western blot analysis.

Results:

MG-132 inhibited C6 glioma cell proliferation in a time- and dose-dependent manner (the IC50 value at 24 h was 18.5 μmol/L). MG-132 (18.5 μmol/L) suppressed the proteasome activity by about 70% at 3 h. It induced apoptosis via down-regulation of antiapoptotic proteins Bcl-2 and XIAP, up-regulation of pro-apoptotic protein Bax and caspase-3, and production of cleaved C-terminal 85 kDa PARP). It also caused a more than 5-fold increase of reactive oxygen species. Tiron (1 mmol/L) effectively blocked oxidative stress induced by MG-132 (18.5 μmol/L), attenuated proliferation inhibition and apoptosis in C6 glioma cells, and reversed the expression pattern of apoptosis-related proteins.

Conclusion:

MG-132 induced apoptosis of C6 glioma cells via the oxidative stress.  相似文献   

10.
Ginseng’s major active components, ginsenosides, have been known to show anti-cancer, neuroprotective, and anti-inflammatory activities. Ultrasonication processed Panax ginseng berry extract (UGB) contains various ginsenosides. The components are different from Panax ginseng berry extract (GBE). This study was aimed to investigate the cytotoxic mechanism of UGB in HepG2 cells, human hepatocellular carcinoma cell line. HepG2 cells were treated with UGB (0, 10, 20 μg/ml). Cell growth and cellular apoptosis were evaluated by MTT assay and Annexin V/Pi staining, respectively. Intracellular Reactive oxygen species (ROS) levels were also determined by 2′, 7′-dichlorofluorescin diacetate (DCFDA) staining. The expressions of Bax, Bcl-2 and caspase-3, the apoptotic markers, were evaluated by Western Blot. UGB dose-dependently inhibited cell growth and induced apoptotic cell death. Intracellular ROS levels were increased. UGB increased the expression of the cleaved form of caspase-3. Furthermore, UGB induced apoptosis of HepG2 cells through Bax activation and Bcl-2 inhibition. In conclusion, UGB induced apoptosis through an intrinsic pathway in HepG2 cells suggesting that UGB might play a role as a novel substance for anti-cancer effect.  相似文献   

11.
Chelerythrine, formerly identified as a protein kinase C inhibitor, has also been shown to inhibit the anti-apoptotic Bcl-2 family proteins. However, recent studies have now demonstrated that chelerythrine can induce the loss of mitochondrial membrane potential (ΔΨm), a membrane permeability transition (MPT), and the subsequent activation of the mitochondrial apoptotic pathway, even in the cells deficient in Bax and Bak. This suggests the existence of an alternative Bax/Bak-independent pathway for apoptosis. The generation of reactive oxygen species (ROS) from the mitochondrial electron transport chain (ETC) is also implicated in the cytotoxity elicited by chelerythrine. In our current study, we show that chelerythrine induces the rapid apoptotic death of H9c2 cardiomyocyte-derived cells within 8 min of treatment. The proteolytic activation of caspase9 and caspase3, crucial mediators of the mitochondrial apoptotic pathway, are also observed within 6 min of exposure to this drug. The generation of ROS is detected but at only marginal levels in the treated cells. The inhibition of the mitochondrial ETC by rotenone and malonate had almost no effects on ROS generation but in both cases effectively inhibited both cell death and the caspase activation induced by chelerythrine. Hence, chelerythrine initiates the rapid mitochondrial apoptotic death of H9c2 cardiomyoblastoma cells in a manner that is likely independent of the generation of ROS from mitochondria.  相似文献   

12.
13.

Purpose

p53 targeted to the mitochondria is the fastest and most direct pathway for executing p53 death signaling. The purpose of this work was to determine if mitochondrial targeting signals (MTSs) from pro-apoptotic Bak and Bax are capable of targeting p53 to the mitochondria and inducing rapid apoptosis.

Methods

p53 and its DNA-binding domain (DBD) were fused to MTSs from Bak (p53-BakMTS, DBD-BakMTS) or Bax (p53-BaxMTS, DBD-BaxMTS). Mitochondrial localization was tested via fluorescence microscopy in 1471.1 cells, and apoptosis was detected via 7-AAD in breast (T47D), non-small cell lung (H1373), ovarian (SKOV-3) and cervical (HeLa) cancer cells. To determine that apoptosis is via the intrinsic apoptotic pathway, TMRE and caspase-9 assays were conducted. Finally, the involvement of p53/Bak specific pathway was tested.

Results

MTSs from Bak and Bax are capable of targeting p53 to the mitochondria, and p53-BakMTS and p53-BaxMTS cause apoptosis through the intrinsic apoptotic pathway. Additionally, p53-BakMTS, DBD-BakMTS, p53-BaxMTS and DBD-BaxMTS caused apoptosis in T47D, H1373, SKOV-3 and HeLa cells. The apoptotic mechanism of p53-BakMTS and DBD-BakMTS was Bak dependent.

Conclusion

Our data demonstrates that p53-BakMTS (or BaxMTS) and DBD-BakMTS (or BaxMTS) cause apoptosis at the mitochondria and can be used as a potential gene therapeutic in cancer.  相似文献   

14.
We have previously reported that gypenosides induce apoptosis in human hepatocarcinoma Huh-7 cells through a mitochondria-dependent caspase-9 activation cascade. In order to further explore the critical events leading to apoptosis in gypenosides-treated cells, the following effects of gypenosides on components of the mitochondrial apoptotic pathway were examined: generation of reactive oxygen species (ROS), alteration of the mitochondrial membrane potential (MPT), and the subcellular distribution of Bcl-2 and Bax. We show that gypenosides-induced apoptosis was accompanied by the generation of intracellular ROS, disruption of MPT, and inactivation of ERK, as well as an increase in mitochondrial Bax and a decrease of mitochondrial Bcl-2 levels. Ectopic expression of Bcl-2 or treatment with furosemide attenuated gypenosides-triggered apoptosis. Treatment with ATA caused a drastic prevention of apoptosis and the gypenosides-mediated mitochondrial Bcl-2 decrease and Bax increase, but failed to inhibit ROS generation and MPT dysfunction. Incubation with antioxidants significantly inhibited gypenosides-mediated ROS generation, ERK inactivation, MPT and apoptosis. Moreover, an increase of the intracellular calcium ion (Ca(2+)) concentration rapidly occurred in gypenosides-treated Huh-7 cells. Buffering of the intracellular Ca(2+) increase with a Ca(2+) chelator BAMTA/AM blocked the gypenosides-elicited ERK inactivation, ROS generation, Bcl-2/Bax redistribution, mitochondrial dysfunction, and apoptosis. Based on these results, we propose that the rise in intracellular Ca(2+) concentration plays a pivotal role in the initiation of gypenosides-triggered apoptotic death.  相似文献   

15.
Yin S  Wang R  Zhou F  Zhang H  Jing Y 《Molecular pharmacology》2011,79(6):1072-1083
Homoharringtonine (HHT) has been reported to be effective in a portion of patients with acute myeloid leukemia (AML) or chronic myeloid leukemia (CML). To investigate its mechanism of action, cell growth inhibition and cytotoxicity of HHT were investigated in three AML cell lines, HL-60, NB4, and U937, and in three CML cell lines, K562, KU812, and KCL22. AML cells were more sensitive than CML cells to HHT-induced cytotoxicity. Using HL-60 cells, it was revealed that HHT decreased the levels of myeloid cell leukemia 1 (Mcl-1), X-linked inhibitor of apoptosis protein (XIAP), survivin, and B-cell lymphoma 2 (Bcl-2)-homology domain 3 (BH3)-only proteins as well as the mitochondrial membrane potential. The levels of Bcl-2, Bcl-2-associated X protein (Bax), and Bcl-2 homologous antagonist/killer (Bak) proteins in HL-60 cells were not changed after HHT treatment. U937, K562, KU812, and KCL22 cells expressed B-cell lymphoma-extra large (Bcl-xL) and were less responsive to HHT-induced apoptosis than HL-60 cells. Silencing Mcl-1 or Bcl-xL, but not XIAP or survivin, enhanced HHT-induced apoptosis in U937 cells. The levels of HHT-induced apoptosis in K562, KCL22, and KU812 cells were inversely correlated with the levels of Bcl-xL but not those of Bcl-2 or Mcl-1. K562 cells expressing high levels of Bcl-xL but no Bcl-2 were less responsive to HHT-induced apoptosis than KCL22 cells that expressed lower levels of Bcl-xL and higher levels of Bcl-2 protein. In K562 cells, knockdown of Bcl-xL, but not of Mcl-1, enhanced HHT-induced apoptosis. Transfection of Bcl-xL into KCL22 cells attenuated HHT-induced apoptosis. These data suggest that Bcl-xL plays a more important role than Bcl-2 and Mcl-1 in protecting against HHT-induced apoptosis.  相似文献   

16.
The molecular changes involved in the induction of apoptosis by vincristine in melanoma have not yet been well defined. Two human melanoma cell lines showing moderate (Mel-RM) and high (IgR3) sensitivity to vincristine were selected from a panel of eight melanoma lines for analysis. Induction of apoptosis was caspase dependent, and was associated with increases in mitochondrial membrane permeability. Vincristine upregulated the expression of Bax, Bak, PUMA, Noxa, p53 and p21 proteins, and downregulated and/or phosphorylated the Bcl-2 protein. Inhibitors of the Jun N-terminal kinase (JNK), but not p38 mitogen-activated protein kinase, significantly inhibited vincristine-induced apoptosis in both IgR3 and Mel-RM cells. In addition, vincristine induced phosphorylation and reduction in Bcl-2 was prevented by an inhibitor of JNK. Downregulation of mRNA for p53, PUMA or Bim by RNA interference had little or no influence on vincristine-induced apoptosis in IgR3 cells. In addition, silencing Bim mRNA did not affect vincristine-induced apoptosis in Mel-RM cells. These results suggest that vincristine-induced apoptosis of at least some melanoma cell lines is dependent on the activation of JNK. The results are consistent with the phosphorylation of Bcl-2 protein, resulting in the activation of Bax/Bak, release of cytochrome c from the mitochondria and the resulting activation of caspases.  相似文献   

17.
Leptomycin B (LMB), which is originally isolated from Streptomyces, possesses anti-tumor properties in vivo and in vitro. Though it was previously reported that LMB induces cell cycle arrest and p53-mediated apoptosis in certain cancer cells, however, the mechanism by which LMB induces apoptosis remains poorly understood. Here, we investigated the mechanisms of apoptosis induced by LMB in U937 cells. Treatment with LMB concentration-dependently induced cytotoxicity and apoptosis in U937 cells that correlated temporally with activation of caspases and down-regulation of Mcl-1 and XIAP. LMB did not change the expressions of Bcl-2 or Bax. A broad spectrum caspase inhibitor, z-VAD-fmk, blocked caspase-3 activation and elevated the survival in LMB-treated U937 cells, suggesting that caspase-3 activation is critical for LMB-induced apoptosis. Interestingly, Bcl-2 overexpression that blocked cytochrome c release by LMB effectively attenuated the apoptotic response to LMB, suggesting that LMB-induced apoptosis is mediated through the mitochondrial pathway. Antioxidants or antioxidant enzymes had no effects on LMB-induced apoptosis. Data of flow cytometry analysis using 2',7'-dichlorofluorescein-diacetate further revealed no reactive oxygen species (ROS) generation by LMB, indicating that apoptosis induced by LMB is ROS-independent. However, the apoptotic response to LMB was not shown in U937 cells pretreated with the sulfhydryl group-containing antioxidant N-acetylcysteine (NAC). Further analysis suggested that NAC directly binds LMB and abolishes the apoptotic effects of LMB. Collectively, these findings suggest that LMB potently induces apoptosis in U937 cells, and LMB-induced apoptosis in U937 cells is related with cytochrome c release, activation of caspases, and selective down-regulation of Mcl-1 and XIAP.  相似文献   

18.
Dioscin, a natural product obtained from medicinal plants shows lipid-lowering, anti-cancer and hepatoprotective effects. However, the effect of it on glioblastoma is unclear. In this study, dioscin significantly inhibited proliferation of C6 glioma cells and caused reactive oxygen species (ROS) generation and Ca2+ release. ROS accumulation affected levels of malondialdehyde, nitric oxide, glutathione disulfide and glutathione, and caused cell apoptosis. In addition, ROS generation caused mitochondrial damage including structural changes, increased mitochondrial permeability transition and decreased mitochondria membrane potential, which led to the release of cytochrome C, nuclear translation of programmed cell death-5 and increased activities of caspase-3,9. Simultaneously, dioscin down-regulated protein expression of Bcl-2, Bcl-xl, up-regulated expression of Bak, Bax, Bid and cleaved poly (ADP-ribose) polymerase. Also, oxygen stress induced S-phase arrest of cancer cells by way of regulating expression of DNA Topo I, p53, CDK2 and Cyclin A and caused DNA damage. In a rat allograft model, dioscin significantly inhibited tumor size and extended the life cycle of the rats. In conclusion, dioscin shows noteworthy anti-cancer activity on glioblastoma cells by promoting ROS accumulation, inducing DNA damage and activating mitochondrial signal pathways. Ultimately, we believe dioscin has promise as a new therapy for the treatment of glioblastoma.  相似文献   

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